Tom brings us back to the point about cartridge compliance and the efficacy of doing a mod like his. I have been thinking about this recently since I installed a van den Hul DDT-II Special in place of my previous Benz-Micro Glider M2.
The vdH's have higher compliances than is usual for most MC carts (and their upper-line models even more so than mine), yet the DDT does not seem to suffer from being run with the same viscous fluid damper settings I used with the Glider. But I'm not sure this would be the case if I had Tom's mod instead of the KAB damper, due to the point I made somewhere above about the added mass imparting not only increased resistance to lateral deflection of the tonearm (as does the viscous fluid), but also continuing intertia once put in motion (which damping fluid does not have).
This sheds some light on a problem that baffled me near the top, namely why Tom felt the mod increased susceptibility to skipping on scratches: it's the intertia - I just didn't put the two together before. There's probably a 'threshold' effect at work: light scratches may actually be less prone to cause skipping with the added weights installed, but these kind of scratches might not normally cause skipping anyway - while scratches beyond a certain magnitude (that acutally cause the stylus to break contact with the groove) may cause a lateral arm deflection that is less easily brought back under control once begun due to the added mass inertia.
Anyway, we see that increased lateral mass mandates matching to a relatively low-compliance cart, such as Tom's Shelter. This is of course no different a concept than the standard one about matching compliance to overall effective arm/cart mass, with the exception that Tom's use of increased *lateral* mass *only* means that there will be little or no effect on system resonance excitability due to infrasonic warps, footfalls and the like, or LF mechanical feedback (which tend to be primarily vertical in nature), nor due to the low bass content of lateral-cut (mono) or diagonal-cut (stereo) recorded music (since the added mass only lowers the resonance point, presumably already below the 20 Hz maximum). So bass performance is enhanced, tracking is maintained, and skipping susceptibility is worsened (but not if your records don't have scratches).
Still, you could say about viscous fluid damping that the bass performance should be likewise increased, tracking may even be slightly improved (fluid does provide a bit of extra vertical damping, though not as much as laterally, due intentionally to the shape of the paddle), and susceptibility to skipping is ameliorated (or at least reduced in magnitude when it occurs). At least one could think so. In my own listening tests with the fluid damper, I mostly heard a cleaning-up of the soundstage, a purer, more extended treble response, and bass that sounded more natural in timbre but not necessarily more extended or dynamic (those tests done with the Glider). I can state that the damper doesn't worsen skipping, but haven't done the tests to state that it really improves this aspect either. In any case, fluid damping does seem to permit the use of carts in any compliance range (indeed, the KAB product, dedicated as it is to the Technics SL-1200 table/arm, will likely be most often used with high-compliance MM carts featuring relatively high-mass tips and cantilevers, such as the models made for club DJ's and hiphop turntablists).
But since KAB evinces no interest in coming out with a fluid damper for Rega-sourced arms (despite my opinion on the market potential there), Tom's mod would seem to be it for owners of such arms - provided (as he states) that they are running a cartridge of suitable compliance. Looked at that way, what he essentially did was come up with a clever method to improve the match of his tonearm to his choice of cartridge, without paying a penalty in reduced trackability. |
TWL: I brought this up before in my post of 8/31/03 (gad, has it really been that long? Where does the time go?!), but I will ask again since you mention it now: Why exactly must the mass be equally distributed on both sides of the (virtual) pivot point with a gimbal 'arm? |
Very interesting approach Twl, but the analogy between stabilizing outriggers on a unipivot design arm and what you've done for your gimbal bearing design arm is somewhat incomplete. Azimuth control should not be a problem with quality bearings in a gimbaled design, but you don't seem to be affecting the center of gravity with your implementation anyway (unlike those "dropped" counterweight Rega retrofits). It seems to me, what you've really accomplished is most similar to what a viscous damping trough arrangement can do, albeit perhaps with lesser attenuation of high frequencies. The goal is to increase the tonearm's resistance to lateral deflections that occur at much higher velocities/frequencies than just the spiral groove's dragging the arm across the record, thus increasing the amount of information able to be transcribed accurately by the stylus. It does seem as though you've hit upon a simple, inexpensive mod to accomplish just that, although I'm curious as to why your mod would actually increase susceptability to skipping - like a viscous damper, it seems as though it should in fact decrease this tendency, since a skip is basically a rapid lateral deflection of the arm. For my decidedly non-audiophile-approved Technics Sl-1200, I intend to soon order a dedicated retrofit viscous damper assembly from KAB, and I hope I'll hear some of the benefits with my Glider that are blowing you away. |
Geez, PsychicA, didn't take long for my post to pull you out of the woodwork...You mean after all this time you didn't 'get' the principle of this gizmo you've been all over me to go ahead and order?! Well, just so's I don't earn one of your 'encouraging' emails tonight, please know that the only reason the damper's still pending in my set-up is because of my recent move - combined with some more urgent upgrade necessities mandated by same, which I now believe I have adequately filled. I promise to get on the phone to Kevin soon... :-) |
Yeah, Viridian, I had wondered before about the angle issue with the Dynavector design, though I hadn't considered a potential resonance problem. I came to the conclusion that the VTA change is probably of no real consequence on a good condition, clamped record, but even if there is enough of a warp to make a difference, the moment of slight misalignment would be over in an eye blink, not a steady-state condition. However, one main virture of their design, whatever it's flaws (and I've never used or heard one), we haven't mentioned yet: It has the potential to greatly *reduce* effective mass in the vertical plane, not only increase it in the horizontal plane. Same VTF accomplished with less mass = less interia, which should result in better tracking, no? |
Twl - I'll try to post here about what I find when I try the damper mod. It also occurs to me that achieving a high level of disparity between the horizontal and vertical tonearm masses is exactly what Dynavector has done for a long while now with their unusual double-pivoted tonearm design.
Animal - The ACE is below the Glider in the B-M lineup. My Glider is the current version "2" series, and has the same 6 X 40um Fritz Geyger mirror-polished stylus as is used on the $1,300 level Wood Body series, for whatever that's worth. |
Basement, all tonearms already incorporate a greater vertical than horizontal resistance into their design (that is to say, beyond the biaxially uniform effective mass of the tonearm/cartridge combo itself) - the Vertical Tracking Force (VTF). Exactly how that tracking force should be calibrated is dictated by the cartridge's suspension compliance (and I would surmise cantilever length/effective tip mass), and is specified for all cart's. Correct VTF achieves the proper balancing act of allowing the stylus to accurately transcribe the vertical accelation of the grooves, while permitting the arm to respond to warps in the playing surface of the record. If you think about it, during set up of a typical tonearm, first the arm with installed cartridge is precisely balanced out by adjusting the counterweight to find the zero VTF calibration point, and then the tracking force is applied by moving the counterweight toward the pivot. Since gravity only affects the arm in the vertical plane, while the VTF is increasing, the amount of inertial mass resistance in the horizontal plane is actually slightly decreasing at the same time, as the counterweight is moved in toward the bearing center. Twl's idea adds back that leveraged mass and more, but keeps it out of the vertical plane of motion.
It would be interesting to know whether there is actually an optimum amount of resistance that should be applied in the horizontal plane, where performance would begin to suffer beyond that point, or whether more is always better up to the practical limits of the bearings, the anti-skating, the cantilever suspension, and the vinyl itself. One easy guess for a safe bet would be to add a calculated effective mass equivalent to 2X the tracking force (1X to bring the horizontal inertial resistance back up to what it was at the VTF zero point, 1X more to bring it up to equal the applied VTF point), since you already know the cart suspension can handle that. But looking at the massivity of the aforementioned Dynavector arm (the vast majority of which appears to pivot only in the horizontal plane), it seems as if it might be safe to add horizontal effective mass orders of magnitude greater than the VTF. (I suppose this is a determination that must be accounted for in linear tracking arm designs? I'm not personally familiar with any of these, but it seems to me that by the end of an LP's worth of play, a lot more mass will have been moved through a much greater distance than with a conventional tonearm.) |
Twl, what you figured out is what I was actually attempting to suggest - hence my description, "...calculated effective mass equivalent..." referenced to the tracking force itself, which is of course measured out at the stylus tip. I wasn't intending to include the arm's mass in the total increase, since it's already there, just to suppose that an increase in the horizontal plane inertial resistance equivalent at the stylus tip to that represented by the applied VTF in the vertical plane would be eminently safe. But again, as probably evidenced by the Dynavector design or a linear tracker, an increase far beyond this, such as you seem to have done, certainly appears to be OK. |
Yes V., I realize that. Still think you'd hear the warp before the change, though, and besides, any heightened tracking ability would tend to make up for this shortcoming in my estimation, but I guess the best solution is not to have warped records! (Which would rule out many of mine...)
Basement, are you refering to a tomearm wrap? I have one of these from Music Direct installed on the integral arm of my Technics SL-1200, just on general principle. It's a ribbon made of very thin, very stretchy black rubbery stuff that sticks to itself, which you wind around the arm in an overlapping spiral fashion. Couldn't vouch for what exactly it does, though. It's been on too long, and too many other things in my system have changed since it was installed (including TT items such as cartridge, mat, and support). Trying to remove it and reinstall it later would probably compromise it physically, it seems to me, so there it remains. I can tell you that the arm does seem well-damped by it (in the sense of not ringing), and that it adds negligable mass. It also stays put quite nicely, and looks quite ugly. |
Well Twl, then you know what the next step is - design and market the commercial version of it! Let me see how it's coming along during the prototype stages if you're going to be looking for investors...
(Come to think of it, if you weren't thinking about designing a whole new arm around this idea, maybe you could just make a retrofit mod kit for Rega arms...shouldn't be too killer, market's there and waiting...) |
Time to go watch "The Sopranos", so I'm being brief. Basement & Twl, my TT/arm was mentioned above (OK, way above), but it is a garden variety Technics SL-1200 with its stock arm. Also as mentioned before, the damper will be from KAB, and it is specifically designed for the Technics (the KAB website has some interesting stuff - check it out). FWIW, the arm is about 11-12g, I believe, which is supposed to mate fine with my B-M Glider M2. If you are familiar with this design, Twl (and who isn't?), you will know that there is no way a weight could be attached to the left side of the horizontal axle, because the sideways-U shaped bracket that fixes the upper vertical bearing is in the way. I'll have to get back to you on the other stuff after the show. :-) |
$49.95 in normal retail = about $79.95 in audiophile retail. What do those dropped counterweight mods sell for? You'll be doing two weights instead of one, so yours should be a bit more. |
I would add to Basement's and Twl's comments about viscous fluid damping, that the fluid becomes progressively more resistive to motion the higher the acceleration factor gets, meaning that the fluid-bathed paddle connected to the tomearm is most greatly damped at the highest frequencies, which means at the onset of transients, which is a Good Thing. The fluid is not very resistive (viscous) at low frequencies (slower accelerations), so it allows the arm to trace the spiral very well, but it probably won't stabilize the arm as much for the bass range as Twl's mass-loading. The flipside to this could be that with a record where the groove wanders a little out of round (a lot of records), the fluid damper would let the arm follow, while the mass-damper may cause the arm to press harder against first one groove sidewall, then the other, as it attempts to trace the ultra-low frequency undulation side-to-side. There would probably not be too much of an audio consequence from this, but if true, the effect would likely cause somewhat greater wear to pressings pronouncedly exhibiting this flaw, indicating that the added weight should be kept as low as is possible to still reap the sonic benefits. |
Basement - Have to say that I too, either do not understand most of your post, or may even disagree with some of it, but my uncertainty about what you have said puts me on hold from commenting specifically. But I am picking up (sorry!) that you are wondering about possibly combining Twl's hoizontal mass increase with fluid damping.
Twl maintains the two perform basically the same function, so this would be unecessary. But this makes me rethink that proposition a little more, and whereas yesterday I was inclined to think the same thing, I now have another thought occurring:
As it regards initial resistance to horizontal arm deflection at the onset of a transient, I would say yes, mass-damping and fluid-damping are probably accomplishing about the same thing. But - as is actually contained within the implication of my last post - there might be a difference extending beyond that initial event, as it concerns inertia. Fluid-damping is essentially free from interial effects. In other words, both mass-damping and fluid-damping will resist being set in motion, but once they are, the mass will tend to want to remain in motion, whereas the fluid will always tend to resist further motion. This suggests that the ideal horizontal mass for accurate transcription of the groove modulation by the stylus/cantilever would be infinitely large, but that the ideal mass for accurate tracing of the groove path (which affects coil-centering) by the cartridge/tonearm would be infinitely small.
I know - no duh! The same is actually true in the vertical plane as well (although here gravity comes into play [and is exploited] as well), and this just brings us back to restating one of the central dilemmas of designing a record playing machine in the first place.
But it does have me fantasizing about things like: A truly ultra-low mass cartridge-carrying system which depends on fluid damping in *both* planes and uses a spring arrangement or equivalent for VTF; Or, how about attempting to capitalize on cutting-edge technology to create an ultra-fast, tonearm-less sensor/processor/actuator system which 'reads' the position of the groove path and record surface height via a laser sensor just in front of the cartridge, and then uses a microprocessor controlling an utra-quick precision actautor mechanism of some sort to positively locate the cartridge body in the optimum position and attitude to enable the stylus to extact the maximum information from the groove modulation through continuous real-time adjustment, possibly incorporating processor monitoring of the cart's signal itself to constantly calculate correct coil-postioning via the electrical L-R separation and phase info? Whew, boy!
(BTW, Twl, I also didn't understand some of your comments responding to my last post, about the run-off groove and degrees and such, or their relevance to my post. Maybe my post itself wasn't clear. Then again, I am eminently unqualified to know what the hell it is I'm really talking about in relation to all this stuff, so rather than worry about incomprehensability due to runaway pedantic excess, I should probably worry about acute embarrassment due to runaway ignorance flaunting! :-)
P.S. Edit: Basement, I wrote this prior to your latest post. |
I will respond to some of your points if I can, Basement. First off, I myself have no direct experience with using fluid damping (yet - I expect to before very long), so all of my information comes from what I have gathered on the subject from various sources, and a lot of my assumptions in the above posts also stem from nothing more formal than just my own common good sense and scientific/mechanical aptitude/intuition (which, believe me, is merely a little better than average, and not the result of extensive education or training). In short, I am no expert.
Your supposition about out-of-phase movement of the cantilever relative to the cartridge body/tonearm, and its causing of positive amplitude errors, is interesting. But do you know for a fact that it is true? I would liken this view of the situation to pumping a swingset for increased altitude, or the cracking of a whip. The other view would be that of trying to push a tackling dummy on a muddy field and having your feet travel the other direction instead - it would result in less motion of the dummy. We could call the first example the "whip-crack" model of relative motion as it affects signal amplitude, and the second example the "traction" model.
The traction model seems fairly straightforward - any unintended deflection of the arm causes a signal undershoot. The whip-crack model would be a good deal more complex. When attempting to push the tackling dummy in the mud, your result will be similar no matter when you engage in pushing. But when cracking a whip or pumping a swing, timing is everything. Get the frequency wrong, and you'll get negative acceleration, not positive. So presumably, the whip-crack model would often show a similar result to the traction model, and only sometimes result in signal overshoot, depending on the conditions of groove frequency, velocity, and amplitude. I do not know which, if either (or even both, under differing dynamic circumstances), of these possibilities is valid.
As far as the Townsend damper design goes (something this thread has enlightened me to), I would surmise the reason he moved the damper out the arm's radius close to the cartridge is because that is where the arm's motion will be greatest in amplitude and velocity, relative to the same damper installed closer to the pivot point as is common. This is very ingenious, as it both increases the effectiveness of the fluid's damping properties, and simultaneously eliminates the cartridge's leverage advantage vs. the normal arrangement, while also ridding the cartridge/damper interface of several inches of potentially resonant and flexible intervening armtube length. It does sound ungainly as hell though (and scary to boot - who wants all that viscous fluid above the record surface?)
I'm not sure I understand the reasoning for the conclusion you draw in your last sentence, since you don't seem to have provided an explanation of why you feel this to be the case (mass being superior to fluid). I would comment regarding your observation about the increase in average arm mass, that this has to be taken in the context of average cartridge compliance - these two parameters evolve hand-in-hand as they must, but it is the compliance issue that leads the dance. My own feeling, as it has developed over the course of this thread, and for reasons I explained in my previous posts, is that a theoretically ideal system would probably be infinitely low in mass in both planes, and hence inertia-less in all directions, and entirely resistively damped, whether by fluid or some equivalent. Of course such is not possible, but it does tend to point away from increased-mass solutions - not that they won't be effective in some ways as well, and maybe even just as good for practical purposes, though I am somewhat skeptical of this right now. |
Very well broken down, Twl. I agree about the fundamental aims you suggest. Your analysis of the probable dynamic response limitation of a fluid damper reinforces the reasoning behind Mr. Townsend's implementation I was expounding on above.
But I must point out a flaw, or at least a simplification, in your characterization of mass-damping as a "static" system. Assuming negligable bearing friction (and this might not always necessarily be the case, but for now I will assume that a premium bearing's friction will fall below the level where it would play a larger role in dynamics), the horizontal mass of the tonearm does not entirely resist the arm's deflection by the cantilever, as you state, but conforms to the basic principle 'for every action, there is an equal and opposite reaction'. In other words, the motion of the stylus will produce deflection in the cartridge/tonearm which is inversely proportional increasing mass of the cart/arm (and also to increasing cart compliance), but this delfection will not = zero, just as in the fluid-damped example. (Had it = zero, you then would have been implying that there existed some 'mass threshold' for deflection, which your unmodified arm hadn't yet crossed, but that had been crossed once you added the extra mass. Of course, and again assuming bearing friction isn't mucking the system up at this point, this isn't the case; there is no 'mass threshold' - it is a continuum, and you have simply moved down the scale in the direction of less deflection.)
What the levels of allowed deflection would actually be in each example of these respective damping systems is unknown to me, and I would guess is likely to remain so. Obviously, in each case there are many variables to be played with that would affect the answer. To achieve an optimum balance of dynamical attributes for any given cart/arm combination, the fluid system allows for relatively easy adjustment via modification of the fluid level, so the mass-damped system should probably feature a method whereby the user can either change the amount of applied mass, or more likely adjust its distance from the pivot point, like a common counterweight adjuster, either by sliding or helical means. (Twl, did I just suggest a major price increase? :-) |
You know, it's been so long since I took a look at the KAB site, I guess I forgot which plane the damping operates in. Considering that the grooves are actually cut at a 45 degree angle, I would suppose that a little of both horizontal and vertical damping would be a good idea (which ties in well with my idealized theoretical above). I'll make a point of asking Kevin at KAB about this aspect.
As far as the threshold hypothesis goes, I can't agree with your analogy about lifting a weight. Weight is not the issue here, mass is. If the weight you couldn't lift was floating in space, and you attempted to push it away from you, you would move both move in opposite directions, according to your respective masses. In theory, when you or I jump up in the air, our push-off sends Earth moving infitesimally in the other direction; there is no real threshold - a practical one, yes, but no absolute one. Or to put another spin (sorry again) on it, if the arm was really so massive that the cantilever's suspension couldn't overcome its mass to move it when transcribing a groove modulation, then it also couldn't move it across the record as it played - the suspension would just keep deflecting until something gave way. If a force applied at the stylus can move the arm at all, then it can move the arm period. |
Was the CD a simultaneously-recorded version of the same session? ;^) |
I've always wanted to see a tensegrity application for some common practical purpose, but there is none I'm aware of. It's just so damn cool, I want tensegrity to be good for something beyond spheroid toys and Kenneth Snelson towers. I doubt a tensegrity stucture would really be useful for a tonearm, but I have wondered whether it may be helpful as an isolation suspension device for components, maybe even TT's. |
Basement, I believe you refering to the yoke.
I am getting a little lost as to where exactly this conversation is now heading, but I will make a couple of observations and hope that they will be relevant (at least to what has been written above, if not to anything important in actual practice).
1) Information in the circa 10Hz range is not intended to be transcribed in the grooves, having been mastered out beforehand. Content in this range is usually limited to warps which are vertical in nature, although a cutting lathe can inscribe rumble of its own, unrelated to the musical signal and horizontally cut.
2) The RIAA curve dictates that bass information is transcribed in the grooves at a much reduced amplitude when the record is cut, then boosted back to flat by the phono preamplifier. So these frequencies do not represent a high physical amplitude at the surface of the record.
3) As Basement implies, DC = an unmodulated groove, i.e., no signal at all. An amp will generally not pass DC, and a loudspeaker does not produce an output from a DC input. Which is to say that there is little pertinence in the notion of 'flat to DC', IMO.
4) Twl's statement about the attack of a tone rising to its fundamental before falling back to DC doesn't jibe with my own understanding. To the best of my knowledge, the attack of an ideal transient event, were it reproduced perfectly in theory, would rise in a straight vertical line over no elapsed time to a frequency = infinity, before falling back smoothly to the fundamental. In practice, transients rise very fast, over a very small span of time, to a very high frequency, before falling quickly but with some ringing back toward the fundamental.
OK, moving right along...
Kevin at KAB is sending me my damper assembly (you still here, Psychicanimal?), so I should have that in hand in a few days. He says that the paddle (which, BTW, is sourced from SME) is curved, and therefore has a damping component in both planes, although he says the vertical predominates - we'll see if that is my impression as well once I actually get it installed. Also, he says there are other paddle profiles available from SME. We had a long and interesting conversation, during which I suggested a product idea he is taking under consideration (completely unrelated to yours, Twl), and I will keep you informed if this goes further (it would likely be only of marginal interest, if at all, to folks on this forum in any case).
Awaiting Nrchy's beta-test results whenever he's a go... |
Alright PsychicA, here you go...
(I'm going to post a version of this report as a separate review as well, since that's essentially what it is, but I do not want to remove it completely from Twl's long-running thread, so here it is in its entirety to continue the conversation - I hope Audiogon doesn't object!)
I got my KAB fluid damper kit for the Technics SL-1200 installed yesterday, and I managed to audition one cut twice in close proximity both with and without the damper, by playing it just before I put the silicone in the trough, and again just afterwards. I also replayed a few other things with the damper activated which I had just played the day before without. So these are my very initial impressions, and since I'm writing this after only one day, I'll have to post any further findings another time if need be.
First of all, let me say that this damper is a very nicely turned-out product, and it doesn't detract in any way from the appearance or operation of my SL-1200, but at half the price I originally paid for my whole TT/'arm new back in the 80's, there's not a lot of perceived value at $150 when you crack open the small foam-lined plastic box and find a little curved machined metal tray (embedded with a set screw for attachment to the 'arm's base, etched with the KAB logo, and painted silver to match the 1200), a tiny plastic paddle with an integral collar and thumbscrew to tighten onto the 'arm (sourced from SME), a syringe of goopy fluid for filling the trough with (sans replaceable cap for storage, an ommission KAB should rectify), some fairly prefunctory instructions, and a hex key, although I don't doubt that KAB's return is fair on this quite specialized accessory. I was unprepared for just how viscous the 'viscous fluid' really was, never having used this type of damper before - that gunk be seriously thick.
In addition, I noted that the paddle which attaches to the tonearm presented less of a resistive 'face' to the fluid contained by the trough in the directions of motion (horizontal and vertical) than I was expecting might be the case (the KAB website has some good new pictures up of the damper in set-up and operation). Its broad side is a bit curved though, in the opposite direction of the curve about the pivot point made by the trough, and it is oriented at a slight angle to both the 'arm's arcing path of horizontal movement through the trough, and to the vertical component of a record warp, since it's not installed pointing straight down from the 'arm, but is offset about 10 degrees toward the direction of the platter.
Let me also just list briefly the audio chain I am listening to this gizmo through:
Benz-Micro Glider M2 .8mv MC cartridge > Technics SL-1200 TT and 'arm (modified with: Symposium shelf underneath sitting on Focalpods soft footers, Michell delrin record clamp, MusicDirect polymer tonearm wrap, and Sorbothane replacement mat) > Camelot Technologies Lancelot battery-powered op-amp phonostage with 54dB gain (modified with 392-ohm Vishay VHS loading resistors and resting on Audioquest Sorbothane pucks) > Cardas Cross 1m RCA IC > InnerSound FET preamp (with Synergistic Research Master A/C Coupler PC) > Harmonic Technology Magic One 1.5m RCA IC > VTL MB-185 Signature circa-200w all-tube monoblocks (with Shunyata PowerSnakes Sidewinder PCs) > Cardas Cross 8ft speaker cable > Thiel CS2.2 3-way floorstanding full-range speakers > and all electronics fed from Audio Power Industries PowerWedge Ultra 116 PLC (balanced AC to front-end components) and supported on a Salamander Synergy Twin 40 rack. Everything is set up a comfortable distance away from walls in a medium-sized living room, with the listening distance being about 10ft.
I listened to three disks from the 60s, acoustic jazz from the Jazz Crusaders LP Uh-Huh, rock from The Who LP Sell Out, and pop from Gary Lewis & The Playboys LP New Directions, and two from the 70s, acoustic jazz from the McCoy Tyner LP Extensions, and rock from the Richard Lloyd LP Alchemy. The Jazz Crusaders 9 1/2 minute cut entitled "Blue Monday" was the track critically auditioned back-to-back first without and then with the damper. Differences noted with the damper in use were pretty consistent across all the cuts I auditioned.
OK, now to the listening. As a preface, let me say that I wasn't expecting huge changes, and I didn't hear huge changes. After all, everything else is staying the same besides the addition of the damper and paddle, so why shouldn't it sound more similar than dissimilar to the sound I have come to expect? I haven't listened for long yet, but I think I do already have a pretty good handle on what this product is going to do for the sound.
I certainly did look foward to some degree of positive improvements for my investment. However, as is often the case in actual practice, the improvements I got turned out to be not the ones I necessarily had in mind when I ordered my unit. I suppose after years of making step-by-step upgrades to my system, I should be better prepared at this point as to just what to anticipate for the next tweak or change. Yet I still manage somehow to be surprised as often as not, a situation which is funny to me, because there are definite similarities underlying a lot of the fundamental improvements I have experienced in the past - such as the principle Less Is Sometimes More.
I decided to acquire this tweak based partly on a set of expectations I had intuited from my deductions about how such a thing must work in operation. I reasoned, if the damper prevents the 'arm from dissapting as unwanted motion energy which should instead be going into forcing the stylus to faithfully transcribe the groove, then I should hear 'more'. More impressive dynamic peaks, more bass slam and weight, more soundstage space, more transient impact, maybe even a little more overall volume. There were a couple of things I was hoping for less of - less surface noise, less HF grain, although I wasn't consciously aware of any objectionable presence of the latter. KAB's inscription on the damper's box promises "deeper bass" and "clearer midrange", as well as "improved tracking", and Kevin A. Barrett (KAB) also mentioned that customers sometimes find more of a sense of 'time slowing down' when listening with the damper fitted, though I don't personally tend to subscribe to such notions myself.
Well, if I had been expecting 'more', in many ways 'less' is what I got, and the things I did get more of were generally not what I had suspected beforehand. In retrospect, everything I heard does make sense given what the damper ought to be doing, but it definitely took my experiencing it to arrive at that conclusion. The very first things I noticed when listening with the damper activated were the cymbals on The Jazz Crusaders cut. They were exhibiting greater HF extension now, and were noticeably smoother. I wasn't expecting that, but I liked it.
I tried to listen for deeper bass, or more explosive transients, but couldn't find them. The soundstage didn't really seem any more expansive than before. The horns did sound a little less foward now, though. When the piano solo came on, I realized that an obsidian-like sort of dark glassiness that had somewhat shrouded the instrument before, had been replaced with a more open, pillowy-natural gentleness as the keys were being purposefully tickled from the outside left rear of the soundstage. When the stand-up bass solo followed, the centered image floated in space just as effectively as before, but had lost a certain talky, PA-like quality to the sound of fingers on strings which had previously rendered it as more of an electronic reproduction of a bass, and instead sounded more naked and true.
I slowly started to realize that although the soundstage wasn't any 'bigger'-seeming, it was effectively deeper, because I could now 'focus my ears', so to speak, more precisely all the way to the backmost reaches and still maintain the sense of clarity and definition. It began to dawn on me that, instead of enhancing the leading edges of transients, what was actually happening was a cleaning-up of their after-effects. Everything within the soundstage was less perturbed by everything else.
Rather than seem incrementally louder, the overall volume, if anything, was actually slightly subdued with the damper doing its thing. But added background texture was reduced even futher, resulting in an apparent universal improvement in S/N ratio. I'm not talking about surface noise as such here, which I didn't notice too much one way or another on these relatively clean disks, but a reduction in what must surely be the artifacts of spurious vibrations and their reflections. The whole presentation sounded tidier, tighter, and clearer, the ever-so-slightly reduced apparent amplitude probably a function of the effective subtraction of reradiated stored energy in the form of ringing. Less is more.
Dynamic events taking place in different areas of the soundstage had less of an effect on one another, permitting the instruments to go about their business without smearing or the imposition of added harshness as compared to before. The result, prehaps paradoxically, was to make gains for my analog reproduction resembling some of the more favorable attributes of CD, for aspects such as separation and contrast, while at the same time actually adding liquidity through the removal of intermodulation. Decays, not the onsets, of transients were the big winners with the damper in place, exhibiting a newfound cleanliness and precision that allowed me follow the flow the music with less guesswork. Image focus became more crystalline-pure and unwaveringly stable, less prone to fluctuate with attacks and crescendos. Although I'm not big on the concept of 'pace', I would actually say that, if anything, the music now seemed to move along at a slightly brisker clip, unencumbered by the dragging disturbance of throwing a larger wake in its trail.
In the big picture, I'd characterize the changes wought by the addition of the fluid damper as being on the order of about 10% or so (quite good), but in the particular areas upon which it has its greatest effects, I'd say they were more like 50%, which I think is excellent. No, I didn't get 'more' bass or dynamics, but I got less of what the presence of such information in the grooves can do to the more fragile parts of the sonic tapestry. In my estimation, what I'm hearing now with the damper is more faithful to the music mastered into the vinyl than what I was extracting previously, mostly through the reduction (if not the outright elimination) of some of the more pernicious effects engendered by the process of attempting to trace microscopic squiggles with a flexibly mounted needle attached to the end of a freely swinging arm.
I have not yet tried to ascertain the improvements wrought, if any, on the trackability of warped records, or the possible effects of the damper on reducing susceptability high-level acoustic feedback, for instance, but I will post updates when/if further developments make themselves known to me. For now I am exploring and enjoying the smoother and cleaner ride through the grooves the KAB damper is affording my cartridge and tonearm. |
Just to keep things perking along here, while we wait for Twl's beta testers to ring in, I remembered a thought recently which first occurred to me quite some time ago, concerning the Dyna 'arm design discussed above.
I actually had this design idea come to me in a dream (talking now about separated pivot points for the horizontal and vertical components, with the vertical bearing being closer to the cartridge), believe it or not, but realized after I woke up that it was merely a variation on the Dynavector. However, this dream was not about the possibility of increasing the horizontal mass per se.
My dream was inspired by the idea of making such a design in order to greatly increase the tonearm length, for more correct tracing of the groove, and therefore lower distortion, by comensurately reducing the angle errors inherent in any pivoted 'arm, while still maintaining a low vertical mass. This remains a valid concept, but one which Dyna declines to exploit in their normal-length 'arm. One could conceivably employ this type of design to make an 'arm, say, 30" long (with the naturally increased horizontal mass that would come from such a long 'arm), and still achieve a low vertical moving mass by placing that bearing point at a more conventional distance from the cartridge. Such a design would address Twl's theory about higher horizontal mass, while offering tracing accuracy much closer to a linear-tracking 'arm. (It would also allow - indeed, require - the decoupling of the 'armbase from the plinth, something which carries with it both potential advantages and disadvantages, or at least inconveniences.) |
Actually, Nrchy, what Twl said was that he was 'a little different' (than what, I don't know); *You* said he was a little strange (but who am I to aurgue?). ;^)
I find it very interesting [Sorry to interupt, but y'know, whenever I see that phrase, 'very interesting', around here (and I use it a lot), I can't help but say it to myself in that faux-German voice Artie Johnson said it in on Laugh-In as he peered through the bushes with his binoculars. Do you think I have a problem? Or maybe I'm just...'a little strange'?] Uhmm, where was I - Oh yes, I find it very interesting that Nrchy and I have seemingly arrived at fairly divergent sonic assessments regarding the tweaks we enacted (I just went back up top to reread Twl's original post, but all he specifically remarks on is increased 'dynamics and detail'). This could lead one to believe that the two tweaks (horizontal mass-increase damping, and fluid damping) are really not that closely related in the ways which they operate. Thinking about it, I'm actually surprised no one has offered (to the best of my knowledge) a retrofittable fluid-damping kit for Rega 'arms, considering how ubiquitous the design is. Another market?
Twl, your idea about the VTA-correcting double-hinged 'arm, while not persuasive to me as such (wasn't it you who said something to me, someplace earlier up this thread, about not getting too complicated - besides, I'm still not convinced that a momentary VTA error of a few degrees during a warp is really a big deal), reminds me of another variation on this theme. I believe I remember a design, probably from the 70's, and probably not all that up-market (although I can't think of who actually may have made this for the life of me), wherein the headshell was hinged on a bearing permitting it to rotate in the horizontal plane, and a separately-pivoted (from the tonearm) 'control arm' was employed, not quite parallel to the tonearm but running alongside it on the outside and swivel-attached at the headshell, for constant correction of the headshell's offset angle as the tonearm moved across the record, through a slight 'parallelogram-ing' action. Anybody know what I'm talking about here ('cause I'm not at all certain that I do!)? I do agree, Twl, that something along the lines of a wishbone, truss, or I-beam design would have to be enlisted to make an extra-long tonearm as rigid and non-resonant as it would need to be. |
Best of luck, Twl, with whatever venture you may undertake to market your idea - have you sought patent advice? I'm just sorry that I can't try it out for myself, as I would love to be able to test this on my own ears. Well, I returned Saturday from a brief out-of-town excursion, and as usual, I came home laden with scrounged vinyl, so at least I have something to console myself with! |
Nrchy, it appears momentum may yet be building slowly... :-) Twl, with Roni on board, what is the grand total of beta-adopters? |
Back to the Tensegrity subject for a sec: Visited Frank Lloyd Wright's Taliesin West in Phoenix recently, and there was an obviously handmade Tensegrity sphere (composed from wooden rods with some kind of natural fiber cord and about a foot in diameter) diplayed sitting atop one of the living room tables and looking fairly old. Unfortunately, our tour guide knew nothing about the object or its provenence, but it seemed solely decorative in purpose. Could FLW himself have toyed with this construction, and also come to the conclusion that fascinating as it was, its only practical application is purely asthetic? |
I haven't given this subject thought for a while, but Jimbo3's new development prompts me to wonder whether it will be problematic in any way to add the weight unevenly (or maybe 'in a statically unbalanced fashion' would be a more accurate description) about the vertical axis (i.e., in the horizontal plane). With the Rega 'arm, the added weight (at least with the lead fishing-weight method) will necessarily be kept concentric with the vertical-bearing axis, since it will be attached to extensions of the axle itself, and the two weights will be added in symmetric, statically-balanced (180-degree opposition) distribution between the two bearing-ends.
If I remember correctly, one reason I never tried this tweak with my SL-1200 tonearm (besides me already having added the KAB dynamic fluid damper, and also not being sure that the bearing-end configuration would be amenable to hosting a fishing-weight attachment anyway) was that the 'arm suspension design features a left-hand horizontal-bearing tower that would preclude adding weight to that side, due to there being no clearance available. In other words, I knew that even if I could get a fishing-weight attached to the bearing-axle end, the only place I could do so would be on the right-hand (one) side, leaving the added weight unevenly distributed about the vertical axis.
But now, thinking about how one would go about adding the maleable 'plastic' weight Jimbo tells us about, and still keep things perfectly symmetrical, has made me reevaluate the importance of this concern. And I seem not to be able to think of a reason why, with a gimballed 'arm, this would be a big deal. After all, I highly doubt that my S-shaped tonearm is statically balanced in the horizontal plane, but dynamically, this doesn't matter.
So it would seem that if I use this product to glom-on some additional weight anywhere I can get it stuck onto the vertical-bearing carriage - statically 'balanced' or not (i.e., without concern for symmetric distribution) - it would produce the desired effect of increasing rotating mass in the horizontal plane only. And indeed, it would be very easy for me to add mass this way with the stuff Jimbo used. Anybody agree/disagree with this conclusion? |
Interesting. It does seem somewhat counterintuitive (in the case of a gimbal 'arm only). Obviously, the situation cannot be totally analogous to an anti-skate hanging weight arrangement, since in that case the connecting piece of line and bracket over which it hangs work together to apply the gravitational force in a lateral vector. Your experiments seem persuasive though, so it would be educational to find out the reason for the observed behavior. I would suppose that to someone with the requisite knowledge of basic dynamics and the fundamentals of the application at hand, this would be a "D'oh!" question, but judging by your own uncertainty, and the certainty of some of your (presumably well-versed) correspondents apparently being at odds with experimentation, perhaps not. As I mentioned above, I don't think that an S-shaped 'arm (such as my own 1200) would be statically balanced in its lateral mass distribution, and the argument could be made that uneven mass distributions as seemingly innocuous as headshell offset or a headshell finger-rest, operating at the distance from the pivot point which they are, should then be almost as disruptive even on a straight 'arm (or could those two factors cancel each other out?). As far as the TT leveling necessity goes, this is of course true anyway - extra weights or no - since the unbalanced (due to the applied VTF) mass of the 'arm/cart is always in play. |
Hi Basement - Your explanation seems to make good sense for a moment, but then it occurs to me: In the case of the balanced lever on a pivot, gravity is working on its mass throughout its length and in equal proportion to the distribution of that mass, while in the case of the 'sideways' tonearm situation, the skating force (unlike gravity) is always being applied unequally only at the point which the stylus touches the spinning vinyl, no matter how the mass is distributed. Is this really analogous?
Shirasagi: You could make a more obvious demonstration by employing the smooth uncut track featured on some test records (older ones anyway) for adjusting anti-skate. The net effect of unequal side-weighting on skating - provided it is present - would be much more readily observable this way than by trying to eyeball the tough-to-see (and impossible to visually quantify with precision) stylus deflection differences. |
I want to go just a bit further and break down just why I feel Tom's idea constitutes a intriguing and enlightening approach. In the past, before coming to some understanding (with the help of the contributors to this thread) of what the HiFi mod represents, I had - I'll assume like most of you - regarded effective mass as a monolithic quantity. Tom's insight made me aware that we should properly take into account two separate quantities of mass, vertical and lateral.
The reports above of those who've tried his mod testifies to the validity of his fundamental underlying proposition: that information retrival may benefit if these two quantities are not treated as being always interchangable - that in fact, performance may be improved if these two quantities are made slightly divergent. Two divergent effective masses instead of one also implies there being two divergent points of resonance (cartridge compliance still assumed to be constant in all directions). I wonder if this presumably 'double-humped' resonance distribution might itself be partly to credit for perceived performance gains, as a result of the altering of the system's "Q" characteristic to be less intensly concentrated at one specific frequency ; in other words, maybe simply making the lateral and vertical mass - and therefore resonance - components somewhat different from each other could be as significant a reason for improvement as the action of additional lateral mass itself.
This an untested hypothetical of course, but we do know that there is a several-Hertz range within which 'proper' system resonance may ideally fall, usually given as from 8 to 12 cycles per second. This value range is considered low enough not to be excited by music, but high enough not to be unduly excited by record warps, big dogs, passing 18-wheelers, distant earthquakes, etc. So there is obviously 'wiggle room' to for instance make the vertical-mass/cartridge-compliance resonance point = 10Hz while the (higher) horizontal-mass/(constant) cartridge-compliance resonance point may be brought closer to say 5Hz without having to worry about extraneous inputs of (primarily vertical) infrasonic energy ruining your tracking day.
The viscous fluid approach , while not imparting inertial effects (and in fact counteracting them), does little to damp such low frequencies, and won't really alter the distribution of the system resonance. (I want to stress here, in relation to this inertia business, that Tom's added weights do not encumber the cartridge suspension in a discriminatory manner that is out of the ordinary ; the suspension must deal with the tonearm's mass inertia anyway, whatever its value. Gravity helps maintain groove contact in the vertical dimension through the VTF setting ; laterally - particularly with really good bearings - it seems to me that inertial mass ought to be able to stand an increase at least roughly equivalent to the VTF.) I observed near the top that fluid damping ought to be superior to the HiFi implementation in terms of HF damping, and this analysis suggests that maybe the two concepts are actually complimentary.
Funnily enough, after so long since this thread began (and after having previously inspected my own tonearm to see if it could be made to accept something like Tom's mod, which I concluded it really couldn't due to its physical design), this late conversation spurred me to go downstairs and look once again - this time with a new notion in mind. And hot damn, there it was: the 1200 tonearm already incorporates added mass in the lateral plane! I'd been looking at it the whole time (the brain sure can work slowly... :-) I think a lot of gimbal tonearms have been made like this: it has a 'carriage' containing the vertical-plane bearings which itself rotates in the horizontal plane (it's mounted within the 'tower' assembly holding the horizontal-plane bearings, which is itself stationary). This 'carriage' structure is basically a rectangle, open in the middle (the arm passes through it), made of cast alloy about 1 1/2" wide by 3/4" tall by 1/4" thick, which incorporates the steel vertical bearings ; when the tonearm moves vertically it remains put, but it rotates in the horizontal plane right along with the tonearm when it is moved laterally. I would estimate its total mass as being roughly in the ballpark of Tom's fishing weights. D'oh! |
Double Bubble. It reinforces the effect of the divergent resonance points... :-)
Tom, your technical analysis of what might constitute the optimum range of added lateral mass and why is a good deal more sophisticated than I could manage (not that I can't follow the gist of it, i.e., what matters are the forces in play at the stylus tip with mechanical multipliers taken into account, not the raw masses involved - I think). So I will just second it with an alternative observation: the existing counterweight on any conventional tonearm is at least as massive as your 24g of added weights, and I would guess probably more often 2 to 4 times that amount, whereas the cartridge, out at the end of the tonearm lever, is roughly 1/2 to 1/4 as massive (as the added weights). At set-up, the counterweight is first balanced against gravity with the cartridge installed, then moved inward toward the pivot to effect the desired vertical tracking force. This action could be seen as 'unbalancing' the cartridge in the lateral plane by the same amount as the applied VTF - and Tom's added weights could be seen as a method of 'restoring' static lateral balance by providing a 'counter-counterweight' that operates only in the lateral plane.
Of course that's not a literally true analogy, because gravity is operating only in the vertical plane, but the lateral accelerations applied by the spinning record at the stylus tip are real, and they can be presumed to be basically equivalent to the vertical accelerations (caused by same) that gravity is enlisted to help manage in the vertical plane. Now, because the groove wall is cut in a 45-degree "V" angle, the downward VTF applies the same restorative force in the lateral plane as in the vertical when the stylus is deflected side-to-side. There is a difference however: in practice, the cantilever is always deflected vertically upward by the VTF, even at rest, whereas laterally it always returns to center. Given that scenario, plus the fact that warps which need to be tracked by the tonearm are mostly a vertical phenomenon, there would seem to be elbow room so to speak for increasing what we might call the 'lateral dynamic tracking force' against which groove accelerations act in the lateral plane. In other words, we can think of Tom's approach (of increasing lateral mass) as effecting a sort of separate, and higher, "VTF" for the lateral plane.
These musings inspire a vision of what Basement refers to as a 'properly designed' (pivoted) tonearm: maybe such a creature would have not just a rear counterweight, adjustable forward and backward to effect proper tracking force, but also side counterweights concentric with the pivot point mounted on extensions of the fixed axle, adjustable in and out from the pivot in order to effect optimal lateral counteractance to forces applied at the stylus - while the whole shebang would be fluid-damped. (And: might such adjustable side-weights even be able to effect some form of dynamic anti-skating compensation?) This seems to me the logical extrapolation of Tom's mod... |
Tom, just to clarify, what I wrote was intended to describe a tonearm having *not only* a conventional counterweight, but *also* side-weights mounted as you specify (I included the detail about bearing-axle concentricity, for instance) - *not* a counterweight with side-weights added to *it*, as it seems you may have aprehended.
Doug, thanks for making clear that you posted earlier about the idea (which I'm sure Tom must have also had from near the beginning) of making the side-weights adjustable. I've thought about this a little more, and come to the conclusion that a production tonearm with this feature would probably need both a provision for threaded-post fine adjustability, plus a small assortment - maybe three different mass values - of exchangable side-weights, to yield a practical working range of variability that's broadly compatible with cartridges of differing compliance. As far as the potential sore point of resonance at the threaded (or whatever) junction goes, I don't think this looks too bad: you already have an adjustable counterweight that's affixed to the tonearm proper, so doing something similar that's on the bearing axle - rather than directly in the tonearm 'mechanical path', such as a detachable headshell - doesn't seem overly daunting to me. |
Speaking of what goes on behind the counterweight, that's where I would work on putting the fluid damping trough, to get the paddle farther from the pivot point than is normally possible on the platter side of things. (The Townsend trough-at-the-headshell-over-top-of-the-spinning-record design notwithstanding, which makes me nervous and seems like it would be a bit of a pain in the butt when it comes to actually playing a bunch of records, although I'm sure that it is the most effective implementation possible from a damping standpoint). So instead of having a relatively massive counterweight very close to the pivot, I'm imagining an extension of the tonearm continuing to the rear, terminating in the damping paddle, with only a relatively light counterweight needed.
I just had an intriguing thought: mightn't Tom's idea be somehow translatable to and beneficial with the Well Tempered tonearm suspension design? |
Doug: Sorry to go off-topic for a sec, but I noticed at soundfountain.com Audio & Music Bulletin that you were using the RSR outer record ring. Did you make yours, or buy it complete? If it was the latter, what do you think of the pricing for the quality? From the text it seems implied that one could be fabricated for my SL-1200, though I don't know if it would fit in between the platter and my KAB damping trough... |
For anyone wondering, I just deleted the post I made here yesterday. I'm working on replacing it with something I hope is a little more sensibly thought-out... |
OK Tom, without going into every detail to the Nth degree, here's what's on my mind now:
First of all, I'm not sure I fully understand why or if it's necessarily desirable to decouple the counterweight. Or to go for lowest mass in general.
But if we assume that these are desirable goals, then why not get completely rid of the coupled mass of the counterweight? Hanging the weight off the end of the tonearm's rear extension seems like it would invite a swinging motion in response to energy inputs at the stylus, since the string can't perfectly decouple the weight. Additionally, the weight would be free to oscillate in response to spurious energy inputs to the plith as a whole, such as from loud bass notes or footfalls.
Today's post is a simpler design then in the post I deleted. End the tonearm at the pivot point, with no extension continuing behind it. Take a cue from the design of a conventional suspended-weight anti-skating arrangement. Hang a weight from a string, run it over a hanger positioned above the tonearm, and attach the string to the tonearm (moveable to fine-adjust VTF). The force of gravity pulling down on the weight now pulls up on the tonearm, offsetting the force of gravity pulling down on the tonearm/cartridge, minus the desired tracking force.
The hanger is mounted on the horizontal bearing housing, in order that there will be no lateral relative motion between the hanger and the tonearm. The hanger (and therefore the weight as well) must rotate along with the tonearm in the lateral plane so that it ignores the lateral component of the tonearm's movements. With the directly-hung counterweight described above, motions of the tonearm in both planes affect the motion of the counterweight. The counterweight 'sees' all the vectors and reacts accordingly. But with an intermediate hanger to run the string over, like is used for anti-skate, motions of the tonearm in both planes have only their vertical component transmitted to the counterweight. The counterweight 'sees' only vertical inputs, and accordingly moves strictly up and down, rather than like a pendulum.
But the counterweight might still move in response to spurious inputs. So, give it a streamlined shape and immerse it a dampening fluid bath. The trough, like the hanger and the weight, will have to ride on the horizontal bearing housing. But this might not be a bad thing, since we removed the mass of the tonearm's rear extension and attached counterweight, and we might want to bump up the tonearm's lateral mass in isolation, like you do with the HiFi mod.
Anyway, if decoupling the counterweight is what we want, then I can't think of many ways to decouple it further than this. I'm just not sure it would accomplish anything... |
Umm...mebbe, but I dunno. I think this one resides in the thought experiment file (along with most of my others :-) For one thing, it violates the KISS principle. For another, a string attached to the tonearm and pulled taut will have a very defined resonance, like a guitar string. But mostly, I just can't fathom why doing this would be beneficial. As opposed to your HiFi concept, which stemmed from an actual theory of its positive effect. I'd just be mucking around in the dark with no clear idea of why. This only occurred to me in response to your post about hanging counterweights, but taken to the max. If I have an opinion on this at all, it's that a conventional counterweight would probably be just as good or better in the real world. But if someone can explain to me why 'decoupling' the counterweight is ever attempted in the first place, maybe I'll change my mind and decide I could be on to something... |
